CD55 in cancer: Complementing functions in a non-canonical manner.

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• CD55 (decay accelerating factor) is a cell-surface protein that regulates complement system activation.
• Loss of CD55 function is linked to pathologies from complement hyperactivation.
• CD55's role in cancer has expanded beyond cell shielding to include intracellular signaling.

Purpose of the Study:

• To review the multifaceted roles of CD55 in cancer progression.
• To explore canonical and noncanonical signaling pathways mediated by CD55.
• To identify therapeutic strategies targeting CD55 in oncology.

Main Methods:

• Literature review of CD55's function in complement regulation and cancer.
• Analysis of intracellular signaling pathways (JNK, JAK/STAT, MAPK/NF-κB, LCK) involving CD55.
• Examination of CD55 expression in cancer stem cell niches and its induction by environmental factors.

Main Results:

• CD55 actively signals intracellularly to drive malignant transformation, survival, angiogenesis, and apoptosis inhibition.
• CD55 is enriched in cancer stem cells (CSCs) within breast, ovarian, and cervical tumors.
• Chemotherapeutics and hypoxia can induce CD55 expression, potentially contributing to chemoresistance and recurrence.

Conclusions:

• CD55 plays a critical, dual role in cancer, acting both as a complement protector and an intracellular oncogenic signaling molecule.
• CD55's involvement in CSCs highlights its importance in tumor recurrence and therapeutic resistance.
• Targeting CD55 presents a promising avenue for novel cancer therapies, though further mechanistic studies are needed.